Compressor bleed control



DCC. 20, C, F SCHORN ET AL COMPRESSOR BLEED CONTROL 5 Sheets-Sheet 1 Filed Oct. 10, 1955 Dec. 20, 1960 c. F. scHoRN ET AL 2,965,285

` COMPRESSOR BLEED CONTROL Filed Oct. 10, 1955 5 Sheets-Sheet 2 Arroz/VIV Dec. 20, 1960 c. F.jscHoRN ET Al. 2,965,285

COMPRESSOR BLOED CONTROL Filed oct. 1o, 1955 5 sheets-sheet 5 Dec. zo, 1960 C. F. SCHORN Em 2,965,285

COMPRESSOR BLEED CONTROL Filed 001'.. l0, 1955 S WIlWWMh/w/w u] 5 Sheets-Sheet 4 @MRA/MAMA Arra/eyv-y Dec. 20, 1960 c. F. scHORN ET AL 2,965,285

COMPRESSOR BLEED'CONTR'OL.

Filed 001'.. 10, 1955 5 Sheets-$11661'I 5 1NVENToR5 v United States Patente COMPRESSOR BLEED CONTROL Carl F. Schorn, Detroit, Leonard W. Keil, Birmingham, and James A. McGrail and Philip -M. Rogers,l Royal Oak, Mich.,.assignnrs to Holley Carburetor-Company, Detroit, Mich., a corporation of Michigan Filed Oct. 10, 1955, Ser. No. 539,346

13 Claims. (Cl. 230v-114) This invention relates to gas turbines,and,more particularly to compressor bleed systemsffor gas .turbine engines.

Gas turbines, especially those adapted for use in propelling military aircraft, are often designed for optimum performance under predeterminedconditions .of operation. This being so, it is apparent `that under other conditions of operation the performance ofthe-engine may be something less thanthat to be desired.

IIn a gas turbine having a twin spool compressor, just for example, a low speed compressor suppliesairl to a high speed compressor, and the compressors-or vrotors as they are sometimes `called are constructedsovthatl the amount of air supplied for optimum.enginelperformance is critical.

Failure to maintain this critical air flow through the compressors` may result in lserious malfunctions-such as stalling of one or more stages oflthecompressorduring acceleration or deceleration of enginespeed. -When stall occurs,engine operation becomesTunstableylwith surging flow and fluctuating discharge pressures-resulting in serious vibration. This may be true,l forexample, when the low speed compressorV suppliesitoo:much air to the high speed compressor, andonemeans of :correcting this situation is to dump or bleed airffrom. the low speed compressor.

The amount of air supplied by the low speed lcompressor is dependent mainly upon its speed and the temperature and pressure of the compressor inlet air.

Accordingly, one object of the invention isvtozprovide an automatic and highly eicient and practical mechanical device that will continuously senserthe speed Of-the low speed compressor, compressor inlet air'pressure and compressor inlet air temperature and combinethe effects thereof into a signal which will open or close a--suita'ble compressor bleed valve at any desired speed, pressurel or temperature condition.

Another object of the invention is to provide afrnechanism of this kind which is pneumatically operatedrra-ther than oil operated. This is desirable because oil at higher temperatures tends to form varnishes and sludge'which may foul delicate valves and other parts of thez'mechamsm.

Still another object of the invention is to provide a device of this kind which is operatedby compressor discharge pressure, which is already available inquantity.

A further object of the invention is to providevsuch a device having means for regulating compressor discharge pressure to provide a constant operating pressure.

A still further object of the invention-isti! provide a pneumatically operated device of this kind having means for metering the amount of compressor dischargeair admitted in order to reduce the temperature withinthfdevice and to thus prevent damage to seals and otherparts thereof.

Other objects of the invention will"b`ecome"more`ap fice Y parent by reference to the following speciiicationsandattached drawings, wherein:

n in greater detail the means for combining ftheeffetyof the sensed conditions into a bleed control signal;

Figure 6 is a side plan view :of ythe. temperature compensating bellows arrangement` shown inend; view in Figures 1 and 3.

Referring to the drawings inqgreater detail, and to the schematic illustrationrin Figure 1 inpartiular,; a Agas turbine engine 10 having a compressor- 12 with high and low speed rotors, a compressor air inlet passagefll and a compressor discharge passage 16 is provided with a compressor air bleed control device-18.

As already stated above, the function of the device18 is to sense the speed ofthe low speed compressor, ycomipressor inlet air pressure and compressor inlet air vtemperature, and to signal one or more interstage 'air bleed yvalves 20 disposed in passages 2.2y toopen or close1' as required in order togbleed the compressor-12pt any.de sired speed, pressure or temperature conditions.

Forthe purpose of sensing the above variables,k thede- Ivice 18 includes a temperature compensatingsystemf24, anlaltitude (pressure) compensating system 126 avfspeed sensing system 28 and a speed sets ystern. ifIhegdeviceg18 is pneumatically operated byy compressoridisn charge pressure, rather than byV engine oil pressuregxfor this purpose, a compressor,` discharge vair pressure Aregul"tina 'and metering system 32, is also provided. f llgof the above systems, which will beldescribedvv individually, cooperate to produce the desired result,-a.nd,.they are upreferably contained within av single housingn34.V

The device l18 and the housing 34 may comprisefany number of convenient.sub-assemblies separated,-or.fen l closed by the usual resilient seals and secured :byfthe usual fastening devices; such partssare welll nownZ in Ythe art and will not vbe described unless necessary. invorder to describe the invention. Various conduits to be-.described in connection with the Yvariousasystems vinayzbe vrprovided between the engine 10 and the device 18.

Y Figure l is intended primarily to illustrate the relation between the engine 1l] and the device v18 andbetwween the various systems of the device 18, and not tov.,a`clcuratelyrillustrate the details of constructionofeithenthe `engine or the device.

Temperature compensating system This system, which is best described by reference to Figures 1, 2 and 3, includes a thermostaticv hollow bulb 36 which is preferably located in the number two position in the compressor air inlet 14 and vwhich has a capillary tube 38 connecting it with la hollow thermostatic bellows 4i). The bulb 36, tube 38, and bellows v40 are filled with a liquid, which varies in volumenotfonly according to the temperature within the chamber 35 in the housing 34 but also according to thetemperature of compressor inlet air as sensed by the/ bulb 36. A liquid filled ambient temperature bellowsizcompensates for the effect on bellows 40 byfthetemperature `of the regulated compressor discharge controlf'air in Y'chamber 35 around the bellows 40 and"42.

Both of these bellows'work against afspringdload which prevents vaporization within the bellows and supplies the return force when the sensed temperature is decreased. This spring force may be provided by resilient means such as compression springs 44 and 46.

Each` of bellows 40 and 42 have a support member 48 mounted thereon, each of which support members 48 is pivoted to an end of temperature bellows lever 50, which lever 50`is pivoted to end 52 of temperature cam lever 54. The central portion 56 of the temperature cam lever 574 is pivoted in bearing 58, and the opposite end thereof having the knob 68 is positioned in the slot 62 in the speed set cam 64.

It will be noted that bellows 4t) is positioned side by side in respect to spring 46 and that bellows 42 is similarly positioned in respect to spring 44; in other words,

` the ends of the bellows 40 and 42 are offset in relation to one another. With this arrangement, expansion and contraction of the bellows 40 and 42 due to variations in the temperature in chamber 35 results merely in the Apivoting of the lever 50 about its center. However, when a change in compressor inlet air temperature occurs, the lever 50 pivots about the pivots 66; this causes the temperature cam lever 54 to rotate the three-dimensional speed set cam 64 about shaft 68 for a purpose to be explained.

Altitude compensating system This system is best shown by Figures l, 3 and 4, and the main parts thereof are the evacuated aneroid bellows 70 having an internal expanding coil spring 72, the aneroid feedback spring 74 seated between the bellows 70 and the member 75 on the adjacent end 76 of the axially movable shaft 68 on which the speed set cam 64 is mounted, the aneroid servo valve 78 which is opened or closed by the lever 80 centrally pivoted at 82 and suitably mounted at one end thereof by means of a ball 84 between the bellows 70 and the spring seat 86, the aneroid slave restriction 88, the aneroid slave piston 90 which includes an axially movable guide member 92 and a high travel diaphragm 94 secured between the guide member 92 and the cylinder 96 and the aneroid slave spring 98 having one end thereof seated on the guide member 92.

Compressor inlet air pressure which is admitted to the chamber 100 from any desired position of the compressor 12 by means of conduit 102 is sensed by the aneroid bellows 70, adjustment of which is provided by screw 104. A load change on the bellows 70 unbalances the equilibrium between the bellows net force output and the aneroid feedback spring 74 and pivots the lcv r 80; this opens or closes the aneroid servo valve 78 so as to change the flow through the aneroid slave restriction 88. The change in ow changes the differential pressure across the aneroid slave piston 90 which in turn causes the speed set cam shaft 68 which is secured for movement with the aneroid slave piston 90 to change its axial position for a purpose to be described and the load of the aneroid feedback spring 74 to return the system to a balanced or null position.

Speed sensing system The speed sensing system is best shown by Figure 2. It includes a drive gear 106 connected to rotate at a speed related to the speed of the low speed compressor, an outer governor shaft 108, radial ball bearings 110 and 112, a compressor bleed governor inner shaft 114, governor fiyweights 116, a thrust ball bearing 11S, a

`compressor bleed governor shaft bearing housing 120 cause their movement is limited by the extent to which the end 128 of the bleed servo lever 132 can move, to exert an input force (parabolically proportional to the speed of the low speed compressor) to the speed set system 30 which is described below.

When the engine 10 is started, the drive gear 196 rotates the outer governor shaft 108 which causes the governor yweights 116 to open until they assume a position determined by the force of governor spring 122.

As speed increases, the yweights 1-16 open further and eventually exert a force against the governor inner shaft 114, which force is in turn transmitted to the compressor bleed governor shaft bearing housing 120. This force causes the governor spring 122, seated on the compressor bleed governor shaft bearing housing 120, to compress when the force against the governor spring 122 becomes great enough to overcome the load preset in this spring. It is apparent then that the bleed servo lever link 130 which is pivoted to the housing 128 at 121 and to the bleed servo lever 132 at 133 moves according to the net applied governor flyweight force, and movement of the bleed servo lever link 130 causes rotation of the bleed servo lever 132 about the spaced pivots 134, the latter being the pivotal connection between lever 132 and the housing 124.

Speed set system This system is best shown by Figures 2-5, and it isso termed because it utilizes the combined elfects of inlet air pressure and temperature on the air bleed control mechanism to determine the speed of the low speed compressor (shaft 108) at which the bleed valve or valves 20 'are to operate. The system includes the speed set cam 64, cam servo lever and support assembly 135, cam servo lever seat 136, cam servo sleeve 138, cam slave diaphragm 140, cam slave-spring 142, speed set roller link assembly 144, speed set lever 148, speed set spring and seat assembly 150, speed set lever link 130, bleed servo lever 132, bleed servo valve 152 and bleed servo sleeve 154.

More specifically, the speed set system 36 functions to establish an equilibrium between the force of the y- `weights 116 and a component of the force of the speed set spring 151, thereby allowing the bleed servo valve (or valves) 152 to assume predetermined positions.

The position of the speed set cam 64 changes, as already described above, in response to the temperature compensating system 24 and the altitude compensating system 26, and these changes cause the cam servo lever 158 to rotate about its supported end 168. The spring 162 eliminates play between the cam 64 and the cam follower 164. The cam servo seat 136 is pivoted on the free end 166 of the lever 158 so that the seat 136 aligns itself squarely on the adjacent end of the cam servo sleeve 138 as the cam follower 164, which may be integral with the end of the lever 15S, senses cam lift changes.

Changes in the position of the cam servo seat 136, relative to the cam servo sleeve 138, permit a change in the differential pressure across the cam slave diaphragm 140, due to the passages 168 and 169 in the sleeve 138 providing communication between the charm ber 35 and the chamber 172 which is vented by passage 173. The cam servo sleeve 138 moves with the diaphragm and its support 174 in response to this differential change 'in order to re-establish the equilibrium position of the sleeve 138 relative to the seat 136. The cam servo sleeve 138 is linked to the speed set roller link assembly 144, so that movement of the sleeve 138 results in movement of the assembly 144.

The rollers 176 on the speed set roller link assembly 144 function as a movable low friction fulcrum between the speed set lever 148 and the bleed servo lever 132, and the variable flyweight force, a measure of the speed of the low speed compressor, is balanced by the'constant force of the speed set spring 15-1 with the help of this V151 to'be applied at a variablefposition' in such a-way that the effect of this spring force increases -hyperbolical- 'lyas the rollers 176 approach the speed setlever pivot H180, at which the speedset lever 148 is pivoted to the housing 124.

The rotation of Vthe bleed e servo Ylever 132, onev or more arms1182 of which may beA pivotally connected to one'l or more bleed servo valvesf152, results in yaxial movement of thev bleed servoevalves 152 within the bleed servo sleeves 154 in a'mannerto cause compressor discharge air supplied by the line 184Mo the bleed servo valvev inlet 186 to move 'the' piston-188 of each `com- 'Ipressor bleed valve actuator 190 in the desired direction foropening orclosing thebleed valves `2l located on the engine f10.

Y Compressor dsclzzrgaa'pressure regulating and meterngsystem This system,-=which is Vbest shown-by Figure 3,regu- 'latesVV and at `thesame 'timeA meters the comparatively Warm' variable 'pressure-compressor --dischargeiair s'upplied "through conduit 184 tofprovide 'the minimum amount of` control air at fa. given constant pressure? above The'y system includes a com- #BellowsVY 192 is l internally "vented to atmospheric #pressurethrough the passages". 198` and 200.1 Unregu'lated compressor discharge pressure, which"enters-'thefchambei' 292 from" thev branch linefZil/', is confined upstream `1'fof`the pressure regulating `@valve'ft94 andV outside. offthe -"bellows 192. p @forcey eiective tolcompressthe'-'bel'lows2192g ori to'open This unregulated pressure fdoes noti exert the valve 194, because the bellowsfeiectivey area is exactly matched by the area of the valve 194 rdisposed within the metering diameter of the .valve seat196. otherwords, the effect of unregulated compressor dischargeV pressure is eliminated.

It will be 'apparentthat the 'bellows-"192l may bead- 1 'justedby meansv suchas'the'adjustment screw`2i26 so that the position of the bellows 192,1 andthe 'valve-194, is determined by the effect of the desired regulated pres- `sure within chamber 35, l5-20 Vp.s.i. above atmospheric for example, acting over the electivearea offthe bel- "lows 192 againstthe rate-ofthe bellows spring 208.

Since :the pressure regulating .'valvef 194* is 1in lseries vvith'the air iiowfpath,fithis^ systemf alsol :functionsf as a ,throttling means, -restrictingltherow-fof"compressori discharge Lair at thesam'eftimeuthat a constantpressure drop is maintained inthe -device=18 'between the :chamber 202 and the outlet 210.

t The following formula, wherein .P4unr'egulated compressor discharge pressure; A1=metering area of'va'lve 194;

P1=control pressure withinchamber v35;

A2=metering area of jet 8S;

P2="pressure regulated by the aneroidservo 78; A3=metering area of thel aneroid servo 7S;

-P3;=pressure regulated by'the cam servo seat 5136;

Air-metering area of Vthe cam vse'rvo'sleeve v138;

indicates that the valve `tdresp'onds both tolchanging .P4 pressure and to'the changing ow ofair through the device 18:

F1ow=KiA1#Pendant/P.;fzJfKaaag/Pr-amospnere +K3A31/Pi-P34-K4A,JP3-atmosphere Thus, the system 3G, inaddition to regulating control 1 1pressure reducesthe amount of hot compressor discharge air introduced into the chamber L35 to the-minimum re- "quired `for operation of `the 'device' 18, --thereby reducing r 6 'tl `theoperating.temperature,thereof.` The above described advantages oli-pneumatic operation: are obtained without the obvious disadvantages of higher t operating `temperas turethat would` result if this utype of..metering-werenot 5; provided for.

` ItV is apparent from-the above specicationand theattached drawingsvthat there has Vbeenfprovided av completely automatic, j pneumatically operated ,mechanical Vdevice which 'continuouslyv senses--the speed --of the llow 10 4speed compressor, `compressor` inlet air temperatureand lcompressor inlet air pressure. The device ythen combines the effects of these important'variables into a singlecon- Ptinuous",signal-whichis used tobleed :the-'compressor .whenevernecess'ary to'extend the; optimumjp'erformance =-of a gas' turbineengineover a wider range of operating conditions.

The device is Veasily adaptable f to `bleed anyi desired stage of any :type of compressor vin anyndesi'red amount. The. device is alsoadaptable'to4 perform anyotheropersation which iscdependent'fupon Athe above variablesl in Hconnection with a 'gas turbine/:engine or-iany :other` device.

f- While the. inventionis ydisclosedin a single preferred embodiment thereof; it: is apparent that certainpl changes may be made therein within the scope of the invention,

andno limitationsvare intendedxexcept as may be required by,v the appended` claims.

What is claimed is: 1,;'l'he combination of agas turbine engine having a casing forming compressor airfinletand dischargepas- Ysages and an iair bleed opening:therebetween,I bleed 'valve means,y in 4.said opening -for. .bleeding fair from. said'l compressor'jand a compressor bleed control device .for openingiand closing said 'bleed valveimeans,1'said'device .comprising double-acting actuatormean's ope'ratedlby unregulated compressor discharge airfconnectedltosand opera*- f .ving saidibleed valve means, servdlvalve:controlled conf duitmeans Y directing... unregulatedfcompressor1 discharge l air to Ssaidractuator mt-raus, a'honsingft'ormet'y tofprovide rstland secondgchambers `'sealed "f-iomlonefzanother Iby a 'ilexiblediaphragm, mechanical lmeans in said iirstch'amber for-sensingl compressori'speedinechanical means in @said first ohamber foroperatinglsaidservo?valve Imeans, Y said two' meansv in said A irst-` chamber beingaoperatively connected,-me'ans fin said 'se'condlchambei ffor# 1 'sensing compressor air inlet pressure, 'separate-means in said'second`chamber forsensingcompressorlinlet air-temperature, said temperaturessensingfmeanstbeing-insensitive to 'variations in control" ambient tempe'rature,l said 'pressure Land-temperature sensing "means'-b`eing--connectedIto v and loperating a *three-dimensional cam combiningLsaid f presf sure and temperature signals; lmeans operatively #connectedi I through saidi ex-ibley 'diaphragmeiandf-fbetween :said camand said mechanical'-means#'PoperatingYsaid-f servo valve=means-`-for utilizing-said combined."pressurev and `temperature signals-'to determine the'compressor'sped at l -whichsaid bleedvalvefmeans shalleopen and close,-said lattermeans and-saidl pressure-sensing means beingy operated by regulated compressor air discharge'pressure' in 50 saidsecondchamber, a-'cnduit supplying compressor Edischarge fair' .to Y said Asecond *chambery andmeans for regulating thepressure-fand-meteringthe-*quantity of saidy lcorr'ipre'ssor` discharge airfsnppliedl to'said second chamber. l A 55 f 22 The combination-of aY 'gas turbine* enginehaving a 'casingrforming compressor'yairinlet'fand dischargepassagesand an'air bleed openingtherebeween, bleed valve *means in said `openingforfbleeding' airfrom'said com- Vfpressor and a compressorble'ed control device'for opening and closn'gsaidV bleed-valve'means, saiddevice connprising double-acting actuator' lmeansfoperated -by unf regulated compressor discharge air connected to -Y and l V`operating vsaid bleedvalve lmeansgservo valve lcontrolled @conduit' means rvdirecting -unregulated compressor 'dis- 'fcharge airtolsaid actuatorrmeans, afhousing-fornied to Ul t provide first and second chambers sealed from one another by a movable wall, means in said first chamber sensing compressor speed, means in said first chamber operating said servo valve means, said two means in said iirst chamber being operatively connected, means in said second chamber sensing compressor air inlet pressure, separate means in said second chamber sensing compressor inlet air temperature, said temperature sensing means being compensated for variations in control ambient temperature, said pressure and temperature sensing means being connected to and operating a three-dimensional cam combining said pressure and temperature signals, means operatively connected through said movable wall and between said cam and said means operating said servo valve means for utilizing said combined pressure and temperature signals to determine the compressor speed at which said bleed valve means opens or closes, said latter means and said pressure sensing means being operated by regulated compressor air discharge pressure in said second chamber, a conduit communicating between said compressor discharge passage and said second chamber, and means in said conduit for regulating the pressure and metering the quantity of said compressor discharge air contained in said second chamber.

3. In a gas turbine engine having a casing forming compressor air inlet and discharge passages and an air bleed opening therebetween, and bleed valve means in said opening for bleeding air from said compressor, a compressor bleed control device for opening and closing said bleed valve means, said device comprising actuator means operated by unregulated compressor discharge air connected to and operating said bleed valve means, servo valve controlled conduit means directing unregulated compressor discharge air to said actuator means, a housing formed to provide first and second chambers sealed from one another by a pressure responsive member, means in said rst chamber sensing compressor speed, means in said rst chamber operating said servo valve means, said twomeans in said lirst chamber being operatively connected, means in said second chamber sensing compressor air inlet pressure and compressor inlet air temperature, said temperature sensing means being insensitive to variations in control ambient temperature, said pressure and temperature sensing means being connected to and operatingra three-dimensional cam, said cam combining said pressure and temperature signals, means operatively connected through said pressure responsive member and between said cam and said mechanical means operating said servo valve means for utilizing said combined pressure and temperature signals to determine the compressor speed at which said bleed valve means opens and closes, said latter means and said inlet air pressure sensing means being operated by regulated compressor air discharge pressure supplied to said second chamber by a conduit, and means in said conduit for regulating the pressure and metering the quantity of said compressor discharge air in said second chamber.

4. In a turbine engine compressor bleed control, a compressor casing having an air bleed opening, a variably positioned, pneumatically operated valve in said opening adapted to discharge air in excess of that required for optimum compressor operation, means responsive to compressor speed operatively connected to position said valve, and means responsive to compressor inlet temperature and operating conjointly with means responsive to compressor inlet pressure operatively connected with said first means to modify the action of said speed responsive means and to vary the range during which said speed responsive means is effective to control said valve, said latter means being powered by compressor discharge air.

5. In a compressor air bleed control for a gas turbine engine having a compressor case with an air bleedopent ing, a pneurnatically actuated air valve yin saidropening for bleeding excessive quantities of air from one or more stages of said compressor, a mechanically operated servo valve controlling the pneumatic forces to said air valve, a three-dimensional cam operatively connected to said servo valve, means responsive to compressor inlet temperature and operatively connected so as to determine the position of said cam, means responsive to cornpressor inlet pressure connected to modify the position of said cam as determined by said temperature responsive means, and means responsive to compressor speed operatively connected to said servo valve and having movement as a function of changes in compressor speed for selecting the point at which said air valve is operable.

6. A compressor bleed device for a gas turbine engine having a compressor case formed to provide compressor air inlet and discharge passages and an air bleed opening therebetween, comprising an air valve in said opening, a double acting pneumatic actuator connected to a source of unregulated compressor discharge air and to said valve in a manner so as to be adapted to open and close said valve, a servo valve controlled conduit connected between said source of unregulated compressor discharge air and said actuator, said servo valve controlling the ow of said unregulated compressor discharge air through said conduit to said actuator, separate means each sensing one of three variables including compressor speed and compressor air inlet temperature and pressure, a second conduit leading from said compressor discharge passage, means in said second conduit for providing a metered supply of regulated compressor discharge air pressure, one or more of said separate means being powered by said regulated compressor discharge air pressure, and means also powered by said regulated compressor discharge air pressure combining the elect of each of said separate sensing means and elective through its connection with said separate means and with said servo valve to control the position of said air valve in response to said three variables.

7. A compressor bleed device for a gas turbine engine having a compressor case formed to provide compressor air inlet and discharge passages and an air bleed opening in said case, comprising an air valve in said opening, a double acting pneumatic actuator connected to a source of unregulated compressor discharge air and to said valve in a manner so as to be adapted to open and close said valve, a servo valve controlled conduit connected between said source of unregulated compressor discharge air and said actuator, said servo valve controlling the ow through said conduit of said unregulated compressor discharge air to said actuator, separate means each sensing one of three variables including compressor speed and compressor air inlet temperature and pressure, a second conduit leading from said compressor discharge passage, means in said second conduit for providing a metered supply of regulated compressor discharge air pressure, one or more of said separate means being powered by said regulated compressor discharge air pressure, and means also powered by said regulated compressor discharge air pressure combining the effect of each of said separate sensing means and effective through its connection with said separate means and with said servo valve to control the position of said air valve in response to said three variables, said latter means including a threedimensional cam the position of which is determined by its connection to the means sensing two of said variables.

8. A compressor bleed device for a gas turbine engine having a compressor case formed to provide compressor air inlet and discharge passages and an air bleed opening in said case, comprising an air valve in said opening, a double acting pneumatic actuator connected to a source of unregulated compressor discharge air and to said valve in a manner so as to be adapted to open and close said valve, a servo valve connected between said source of unregulated compressor discharge air and said actuator, said servo valve controlling the ow of said unregulated comcludingcompressor speedfand compressor air inlet temperature and pressure', said` means-sensing air inlet temperature having means to eliminate the etfect of varying ambient temperaturein 'said device, la conduit between said compressor -discharge ypassag'eand said housing, means in said conduit for providing a' metered 'f'supply of regulated Y'compressor discharge-air pressureg'one -or more of said separate means being powered by said regulated compresi sor discharge ai-r pressure, and means also powered by said regulated compressor discharge air pressure combining the effect of said separate sensing means and effective through its connection with said separate means and with said servo valve to control the position of said air valve in response to said three variables.

9. A compressor bleed device for a gas turbine engine having a compressor case formed to provide compressor air inlet and discharge passages and an air bleed opening in said case, comprising an air valve in said opening, a double acting pneumatic actuator connected to a source of unregulated compressor discharge air and to said valve in a manner to be adapted to open and close said valve, a servo valve connected between said source of unregulated compressor discharge air and said actuator, said servo valve controlling the flow of said unregulated compressor discharge air to said actuator, a housing containing separate means each sensing one of three variables including compressor speed and compressor air inlet temperature and pressure, a conduit between said compressor discharge passage and said housing, means in said conduit for providing a metered supply of regulated compressor discharge air pressure, one or more of said separate means being powered by said regulated compressor discharge air pressure, and means also powered by said regulated compressor discharge air pressure combining the eifect of said separate inlet air temperature and pressure sensing means and effective through its connection with said separate speed sensing means and with said servo valve to control the position of said air valve in response to said three variables.

10. A compressor bleed device for a gas turbine engine having a compressor case formed to provide compressor air inlet and discharge passages and air bleed opening in said case comprising and air valve in said opening, a double acting pneumatic actuator connected to a source of unregulated compressor discharge air and to said valve in a manner so as to be adapted to open and close said valve, a servo valve connected between said source of unregulated compressor discharge air and said actuator, said servo valve controlling the ow of said unregulated compressor discharge air to said actuator, a housing containing separate means each sensing one of three variables including compressor speed and compressor air inlet temperature and pressure, a conduit between said compressor discharge passage and said housing, means in said conduit for providing a metered supply of regulated compressor discharge air pressure, one or more of said separate means being powered by said regulated compressor discharge air pressure, and means also powered by said regulated compressor discharge air pressure combining the effect of said separate inlet air temperature and pressure sensing means and effective through its connection with said separate speed sensing means and with said servo valve to control the position of said air valve in response to said three variables, said connection with said speed sensing means including a spring and lever mechanism providing a mechanical advantage causing the xed force of said spring to be effectively changed parabolically with changes in compressor inlet temperature or pressure.

l1. In a gas turbine engine having a compressor casing formed to provide compressor air inlet and discharge passages and a compressor air bleed opening, a device for bleeding compressor air through said opening, said 'l device comprising avalve'- in 'said Iopening; a" two-'Way sourceof'unregulated compressor discharge air pressure,

a' servo valve connected between said actuator and said 'source'of'unegulated air pressure `and'lcontrolling the iiow of said air to said actuator, rst means for 'producing a continuoussignal inresponse to compressor air inlet temperature, the signal from said rst means not including anyeffectbf changes inlambient temperature in said device, second means for producing a continuous signal in response to compressor air inlet pressure, a three-dimensional cam connected to said first and second means in a manner so that the position thereof is dependent upon a compressor air inlet temperature and pressure, third means for producing a continuous signal in response to compressor speed, a housing for said signal producing means, a conduit between said compressor discharge passage and said housing, means in said conduit supplying a metered source of regulated compressor discharge air pressure, and means responsive to cam position and to said compressor speed signal connected to and controlling said servo valve, said latter means being actuated by regulated compressor discharge air pressure.

12. In a gas turbine engine having a compressor casing formed to provide compressor air inlet and discharge passages and a compressor air bleed opening, a device for bleeding compressor air through said opening, said device comprising a valve in said opening, a two-way pneumatic actuator connected to said valve and to a source of unregulated compressor discharge air pressure, a servo valve connected between said actuator and said source of unregulated air pressure and controlling the ow of said avr to said actuator, first means for producing a continuous signal in response to compressor air inlet temperature, said first means being arranged so as to eliminate the effect of changes in ambient temperature in said device, second means for producing a continuous signal in response to compressor air inlet pressure, third means for producing a continuous signal in response to compressor speed, a three-dimensional cam connected to two of said means in a manner so that the position thereof is dependent upon the respective signals produced thereby, a housing for said signal producing means, a conduit between said compressor discharge passage and said housing, means in said conduit supplying a metered source of regulated compressor discharge air pressure, and means responsive to cam position and to the other of said signals connected to and controlling said servo valve, said latter means being actuated by regulated compressor discharge air pressure.

13. In a gas turbine engine having a compressor casing formed to provide compressor air inlet and discharge passages and a compressor air bleed opening, a device for bleeding compressor air through said opening, said device comprising a valve in said opening, a two-way pneumatic actuator connected to said valve and to a source of unregulated compressor discharge air pressure, a servo valve connected between said actuator and said source of unregulated air pressure and controlling the tlow of said air to said actuator, iirst means for producing a continuous signal in response to compressor air inlet temperature, said rst means being arranged so as to eliminate the eiect of changes in ambient temperature in said device, second means for producing a continuous signal in response to compressor air inlet pressure, a three-dimensional cam connected to said rst and second means in a manner so that the position thereof is dependent upon compressor air inlet temperature and pressure, third means for producing a continuous signal in response to compressor speed, said third means including a centrifugal governor and a spring arranged so that the output force of said spring is parabolically proportional to compressor inlet temperature or pressure, a housing for said signal producing means, a conduit having References Cited in the le of this patent UNITED STATES PATENTS 2,404,324 Staley July 16, 1946 10 12 Ruby Ian. 24, 1956 Lombard Apr. 10, 1956 Lombard et a1. Mar. 19, 1957 Chapman June 3, 1958 FOREIGN PATENTS Great Britain July 15, 1948 Great Britain Aug. 17, 1955 France Apr. 4, 1955 Q ...rms 

